Whole body scintillation detector for animal use comprising a plurality of plastic phosphor rectangular logs



Aprll 2, 1968 c, c ET AL 3,376,417

WHOLE BODY SCINTILLATION DETECTOR FOR ANIMAL USE COMPRISING A PLURADITY0F PLASTIC PHOSPHOR RECTANGULAR LOGS Filed May 31, 1966 6 Sheets-Sheet lv I INVENTORS CHARLES R. KECK PA U L W. J O R DA N April 2, 1968 R K ETAL 3,376,417

WHOLE BODY SGINTILLATION DETECTOR FOR ANIMAL USE COMPRISING A PLURALII'YOF PLASTIC PHOSPHOR RECTANGULAR LOGS Filed May 31, 1966 6 Sheets-Sheet"M'lb a 1%! INVENTORS CHARLES R. KECK PAUL W. JORDAN ATTORNEYS April 2,1%68 c. R. KECK ET AL 3,376,417

WHOLE BODY SCINTILLATION DETECTOR FOR ANIMAL USE COMPRISING A PLURALITYOF PLASTIC PHOSPHOR RECTANGULAR LOGS Filed May 31, 1966 6 Sheets-SheetINVENTORS CHARLES R. KECK 4 PAUL. W. JORDAN ATTORNEYS A ril 2, 1968Filed May 31, 1966 COUNTS PER SECOND COUNTS PER SECOND c. R. KECK ET AL3,376,417

WHOLE BODY SCINTILLATION DETECTOR FOR ANIMAL USE COMPRISING A PLURALITYOF PLASTIC PHOSPHOR RECTANGULAR LOGS 6 Sheets-Sheet 1 13? AT CENTER ATCENTER K40 AT END "A" o lo so s0 10 a0 I00 PULSE HEIGHT 0 13? AT END Kmsrmeureo souacs I l D I l l PULSE HEIGHT !NVENTORS CHARLES R. KECK RAULW. JORDAN ATTORNEYS Apr-1B 2, 1968 KECK ET AL 3,376,417

WHOLE BODY SCINTILLATION DETECTOR FOR ANIMAL USE COMPRISING A PLURALITYOF PLASTIC PHOSPHOR RECTANGULAR LOGS Flled May 31, 1966 6 Sheets-SheetLIGHT COLLECTION Q (VIEWED ONE END ONLY) HEIGHT PULSE ELATIVE 1 u l 1 lx I I 1 1 I2 IO 8 6 4 2 O 2 4 6 8 IO l2 DISTANCE FROM CENTER (Inches)SUM RELATIVE PULSE HEIGHT I J I I l I L I I I I l -l2lO8-64202468l0DISTANCE FROM CENTER (Inches) F/G. l2

INVENTORS CHARLES R. KECK PAUL W. JORDAN ATTORNEYS April 2, 1968 C.WHOLE BODY SCINTILLATION R. KECK ET AL DETECTOR FOR ANIMAL USECOMPRISING A PLURALITY OF PLASTIC PHOSPHOR RECTANGULAR LOGS Filed May31, 1966 COUNTER 6 Sheets-Sheet i;

+1 RECORD RATE METER VOLT METER "LOAD CELL INVENTORS CHARLES R. KECKPAUL W. JORDAN ATTORNEYS United States Patent 0 3,376,417 WHOLE BODYSCINTILLATION DETECTOR FOR ANIMAL USE COMPRISING A PLURALiTY 0F PLASTICPHOSPHOR RECTANGULAR LOGS Charles R. Keck, Morris Road, Okmulgee, Okla.74447,

and Paul W. Jordan, Montana State University, Bozeman, Mont. 59715Continuation-impart of application Ser. No. 443,374, Mar. 29, 1965. Thisapplication May 31, 1966, Ser. No. 554,051

3 Claims. (Cl. 250-715) This invention relates to a method and apparatusfor efficiently measuring the total lean meat content of live animals.It makes use of low level radiation naturally emitted from the bodies ofanimals and applies a scintillation technique to compute the lean-to-fatratio.

The present application is a continuation-in-part of my application Ser.No. 443,374, filed Mar. 29, 1965, and entitled, Apparatus forDetermining Lean-to-Fat Ratio in Cattle.

Naturally occurring potassium is concentrated only in the lean tissuesof all living animals. Bone and fat contain little or no potassium. Thepotassium isotope K naturally emits radiation. Our invention utilizes alowlevel gamma radiation counter to measure the radiation emitted fromthe K thereby giving an indication of the lean meat content of theanimal.

Since more than ninety-seven percent or" the potassium in the body isintracellular, any change in the total amount of potassium reflects achange in the ratio between the lean protoplasmic mass to the mass ofbone and fat. The amount of potassium can be measured by counting thenumber of naturally occurring bursts of gamma radiation from K within agiven time. Thus, it is not necessary to inject radioactive materialinto the animal, thereby contaminating the meat. Instead, gamma from Kis constantly being radiated by all living animals, and can undersuitable conditions, be measured.

Our invention is a variable research tool for the domestic animalindustry, and will beneficially affect herd development and feedingprograms. Since the lean meat characteristics of beef animals, forexample, are 70% inheritable, it can be seen that by measurement of thelean meat content of both the sires and dams of the herds, and thesubsequent selection of the high-ratio lean animals, a high lean meatherd could be developed very rapidly.

Furthermore, feeding studies indicate that the amount of lean meat puton by fast weight gaining animals, is

generally put on during the early part of the feed program, and the fatis produced in the final feeding. The amount of feed generally requiredto put fat on an animal is about twice as much as required to put onlean meat. Therefore, if measurements are taken at weekly intervals, theexact amount of lean meat gain could be determined, and the animalslaughtered at the appropriate time, without wasting feed to produceundesired fat.

In the past, several methods have been used to determine the lean meator carcass characteristics of live animals. These range all the way fromeyeballing the live animals by experts, through correlation of recordsof birth, weight through final weights, predicting wholesale cuts byphotogrammetric measurements, estimating the body fat from anesthesiainduced sleep, use of high frequency ultrasonic devices, and progenytesting. Each of these methods has limitations due to human error or thelength or" time required before any constructive action can beinitiated. The purpose of our invention is to overcome the defects ofthese previous methods utilized to determine lean meat characteristics,and to provide a method and apparatus for efiiciently and accuratelydetermining the lean meat or muscle characteristics of animals.

It is therefore. an object of invention to provide a method andapparatus for non-destructively determining the lean meatcharacteristics of domestic animals efiiciently and accurately.

It is another object of invention to provide a method fornon-destructively grading domestic animals according to the lean meatcharacteristics in order to control breeding and the production of typesof animals with the desired lean meat characteristics.

It is another object of invention to provide useful measurements of thelean meat characteristics of domestic animals to develop and control thefeeding program, with a view towards minimizing the use of feed for theaccumulation of fat on the animals prior to slaughter.

It is another object of invention to provide apparatus to render thescintillation measurement technique of K in domestic animals accurateand economically feasible for use in commercial applications.

It is another object of invention to provide an apparatus for measuringlean meat characteristics in animals, which is easily transportable, sothat it may be used both during the breeding and feeding stages ofanimal development.

It is another object of invention to reduce the shield weight of theapparatus used to measure the lean meat characteristics of domesticanimals, to thereby reduce the total weight of the apparatus.

It is another object of invention to eliminate the eifect of undesiredradiation, which have accumulated on the animals hair and hide by eithernature or manmade tall-out, in order to provide an accurate K count ofthe animal.

It is another object of invention to provide apparatus for accuratelymeasuring the K isotope present in the lean meat of domestic animals.

It is another object of invention to provide an apparatus to measure awide range of the lean-to-fat ratio of different sized animals.

It is another object of invention to provide radiation detectorequipment, in a particular geometrical configuration, in order toprovide accurate K measurement, as well as to provide for measuring avariety of different sized animals.

It is another object of invention to provide a particular detectorshape, in combination with photomultiplier tubes, to obtain accurate Kmeasurements.

These and other objects of invention will be apparent from the followingspecification and drawings in which:

FIGURE 1 is an isometric view of the trailer and measuring equipmentconstructed in accordance with the principles of the present invention;

FIGURE 2 is a side view of the cattle squeezer, which is utilized tosecurely transport the cattle to and from the measuring equipment;

FIGURE 3 is an end view of the cattle squeezing apparatus;

FIGURE 4 is a sectional view, partially cut-away, of the detectionchamber, illustrating the phosphor detectors and the photomultipliers,taken along the section lines 4-4 of FIGURE 5;

FIGURE 5 is an end view of the detection chamber, illustrating thephosphor block-photomultiplier geometrical configuration;

FIGURE 6 is a perspective view of the plastic phosphor block utilized inthe present invention;

FIGURE 7 is a graph showing the relative pulsehei'ghts produced by ascintillation detector, which comprises a rectangular log 6" x 6" x 60",with two multiplier tubes, one at each end, but without light pipes;

FIGURE 8 is graph showing the measurements of a scintillation detectorof a log 6" x 6" x 60", with light pipes, showing the relativepulse-heights produced by C and K FIGURE 9 is a graph illustrating therelative pulseheight obtained relative to distance from the end of thephosphor, viewed from one end only;

FIGURE 10 is a block diagram of the electric circuitry utilized in thisinvention;

FIGURE 11 is an isometric view of the animal squeezer; and

FIGURE 12 is a graph illustrating pulse heights obtained relative todistance from both ends of the phosphor log, as well as the sum of bothpulses and the eliminated good A and B.

With regard to the detection of radioactive potassium, K, it has beenestablished that there is a constant ratio between the natural abundanceof the stable atoms of potassium, to those of the radioactive isotopes.Among the radioactive isotopes, K is potentially the most easily useableradioactive isotopes because of its relatively long half-life andnatural occurrence in living tissue. Microquantit'ative analysis hasshown that the amount of K in any potassium sample varies less than10.03%. Further, the decay pattern of potassium 40 is characterized by afairly energetic gamma. Accordingly, because of the characteristicradiation energy of the gamma radiation, potassium 40 acts as 'anexcellent tracer.

Furthermore, chemical analysis has proven that the amount of K containedper unit weight in the lean tissue of animals is constant and remainsrelatively unchanged throughout the life of the live organism. It hasalso been found that any change in total potassium content refiects achange in the ratio of lean protoplasmic mass to the mass of bone andfat which contain little or no potassium. Therefore, while it isapparent that no two bovine metabolic systems are identical, thepotassium content is nevertheless essentially constant for any givenlean tissue and has been determined to be an average of 0.91 gram perpound of lean body tissue. Thus, because of its natural occurrence inthe aforementioned constant ratio to the lean meat content of animals,detection of the radiation emitted by the K forms an excellent basis foraccurate determination of the lean ratio. This determination plus aknowledge of total body weight enables a determination of bodycomposition or, in other words, lean-to-fat ratio.

Referring to the drawings in detail, FIGURE 1 illustrates a mobileapparatus generally referred to by reference numeral 2, by means ofwhich rapid, relatively accurate and non-destructive testing of animalsmay be performed in accordance with the principles of the presentinvention. So as to render the apparatus mobile, and to provide easytransportability, the total weight of trailer 2 should be such that itfalls within the range allowed on public highways.

Trailer 2 is supported by wheel assembly 4 at one end, and retractablejack mechanism 7 (not shown) spaced from the other end. It is alsoprovided with hitch 6 to provide easy connection of the trailer to thecab section of a truck for transportation. Also mounted on the trailer 2are enclosures 74 within which the electronic monitoring and measuringfacilities may be housed, as well as other equipment. Also mounted onthe platform intermediate the opposite ends thereof, is radiationdetector chamber within which the detecting means are located.

The detection chamber 50 comprises a five inch thick steel radiationshield 3 which forms the top, walls, and one end of the chamber.Additionally, five inch thick steel doors 8 are mounted on rollers, andfurther act as a shield from unwanted radiation which would cause aninaccurate K letermination. The radiation chamber is then enclosed by aninsulated aluminum van cover 70.

Ramps 8 and 10 are detachable from the trailer. To-

gether with gates 12, 14 and 16 they provide for the entrance and exitof the animal to squeezer 20. In the position of the gates illustratedin FIGURE 1, animals will climb up ramp 8 through gates 1216, intosqueezer 20. Gate 14 is pivotably mounted to support 18, and when it isdesired to transport the animal into the detection chamber 50, gate 14is moved to the position wherein it simultaneously closes oif ramp 8,and permits squeezer 20 to be transported along rails 48 and 48 into thedetection chamber 50. This is illustrated by the broken line position ofgate 14 in FIGURE 1. A scale of the type employing conventional loadcells may be positioned at the bottom of squeezer 20 so that the animalmay be weighed prior to counting. The correlation of body weight to Kcount determines, of course, the lean to body weight ratio.

After measuring the lean meat characteristics, the squeezer containingthe animal is transported back along rails 48 and 48' to the positionshown in the drawings. The animal is then released down ramp 10 and gate14 is returned to the original position illustrated in FIGURE 1. Animalsreleased from the squeezer 20 may therefore leave the trailer throughthe exit ramp, while ,at the same time, another animal may be loadedinto the squeezer. This process continues until all animals have beenmeasured.

The purpose and function of the animal squeezer is more clearly definedin FIGURES 2 and 3. FIGURE 2 shows that it is mounted on truck 22, whichis provided with wheel assembly 24 to ride rails 48 and 48' for easytransportation of the animal squeezer 20. Truck 22 further comprises atable surface 26 upon which the animal stands. Table 26 is variable inthe vertical direction by hydraulic lift 30, operable by motor 28. Whenit is desired to raise the table, hydraulic lift 30 forces rigid arepivotably mounted together and are rigidly secured in track 33 i rod 32along track 33. Rods 32 and 32 by wheels 34. The movement of rods 32 and32 towards each other, causes the upwardmovement of table top 26.Conversely, the movement of rods 32 and 32' away from each other causesthe downward movement of table 26. It is apparent that verticaladjustment is necessary in order to properly position the immobilizedanimal within the detection chamber 50 when the radiation reading istaken.

As illustrated in FIGS. 3 and 11, walls 36 and 36' are securelypivotally mounted to table 26, and are. also mounted via rollers 38 and38' to run in a track on end walls 40 and 42. Thus, as the animal is fedinto the animal squeezer '20, table 26 is raised until the animal ispositioned at the top of the cage defined by end walls 40 and 42, and bysemicircular bars 44 securely mounted to the side walls 36 and v6. Endwall 42 securely positions the animals neck and head.

When the animal is in the detection chamber, it is essential that he belocated in a position near the plastic phosphor detectors. The purposeof table top 26 is to position different sized animals correctly inrelation to the plastic phosphor blocks. The table top 26 furtherfunctions with side walls 36 and 36 to squeeze the animal in position sothat he cannot move about.

As table 26 is raised, walls 36 and 36' via rollers 38 and 38' will beforced upwardly along the track. Because of the circular configurationof end walls 40 and 42, and because walls 36 and 36' are rigid and aresecurely mounted to table 26, this will cause a lateralmovement of walls36 and 36 towards each other. This is illustrated in FIGURE 3, in whichthe broken lines illustrate the position of walls 36 and 36' when table26 is in its furthermost raised position. The movement together of walls36 and 36' will thus ,squeeze the animal so that it is securelypositioned in squeezer 20. This is essential, since movement of theanimal during measurement of the leanto-fat ratio, could causeinaccuracies in the measurement,

as well as damage to the detector.

It will therefore be apparent that the animal handling procedure notonly facilitates rapid processing of the animals, but also arranges forthe proper orientation of the immobilized animal within the detectionchamber so that an accurate measurement of the radiation emittedtherefrom may be made.

FIGURE 5 illustrates the configuration of the circular plastic phosphorradiation detector 52 which is positioned on a roller support at therear end of chamber 50. Support 52 is movable along tracks 48 and 48',in the center of the radiation detector chamber 50. Severalphotomultipliers 56 are mounted on the back side of the circularphosphor radiation detector 52, their purpose to be explainedhereinafter.

FIGURE 4- is a top plan view of the detection chamber, which ispartially cutaway, and which therefore illustrates only one of thephosphor logs 60. A plurality of the rectangular log phosphor radiationdetectors 60 are positioned within the chamber on a support ring at eachend, for measurement of the carcass ratio.

Photomultipliers 62 are securely attached to each end of each log 60.The logs 60 are located around the radiation detection chamber 50 in ahorseshoe configuration as illustrated in end view FIGURE 5, as well asin isometric FIGURE 1.

Plastic phosphors are used in the detector equipment to measure the Kcount from the animals. Some of the reasons for using plastic hosphorsare as follows:

(1) The light output of the better quality plastic phosphors approachesthat of the best liquid scintillators and offers certain advantages:

(a) freedom from poisoning by atmospheric oxygen and.

trace environmental impurities (b) complex mounting problems are greatlydiminished (c) easily machined and formed into special shapes.

(2) Plastic phosphors provide the following advantages over inorganiccrystals such as NaI (Tl):

(a) shorter decay time (b) non-hygroscopic (0) less susceptible tothermal and mechanical shock (d) easily machined and formed into specialshapes (e) lower cost.

The blocks or logs 60 utilized are approximately 6" x 6" x 60 althoughthe specific dimensions are not pertinent to the basic principles ofthis invention. Each log or block is highly polished, and the end ofeach block is optically coupled to a photomultiplier tube 62 asillustrated in FIGURES 4 and 5.

Phosphor logs 60 are made of a material which will, upon contact withgamma radiation, produce tiny bursts of light or scintillationscorresponding to the passage of gamma rays therethrough.

After the conversion of gamma energy to visible light quanta by thephosphor, the light is transmitted by the plastic through a process oftransmission and multiple reflection to each end of the log. Each end ofthe detector is optically coupled to a photomultiplier tube 62 whichproduces a pulse of elecrtic current every time a burst of light occurs.The height of the pulse varies directly with the strength of the burstof light. Because of the use of a photomultiplier tube at each end ofthe phosphor log, a greater amount of phosphor can be viewed by eachphotomultiplier tube, than in any known configuration heretofore in usewith no loss, or in some cases an improvement in resolutions ashereinafter explained.

The use of highly polished phosphor blocks in the special shape andconfiguration disclosed, permits the blocks to function both as a lightpipe and scintillation detector. The pulse-height resolution from agamma source which contacted a plastic phosphor block without lightpipes 30 inches from a photomultiplier tube is shown in FIGURE 7. FIGURE8 shows resolution using a distributed source such as is obtainedthrough a rectangular plastic log with light pipes, according to thepresent invention.

Furthermore, by this method of end viewing in which no protruding tubesin a direction lateral to the long dimension of the detector are used, agreat saving in space is effected. This in turn reflects in such reducedshield weights that the detector design disclosed greatly enhancestransportability of the trailer. Thus, the K radiation within the leantissue of the animal is detected by a plastic phosphor detector whichconverts the gamma energy to light quanta. This light quanta istransmitted optically along logs which also act as a light pipe to thephotomultiplier tubes, and is then connected to the electric circuitrywhich will hereafter be described.

Another species of logs which may be used were also developed. Thisinvolved the utilization of a bundle of scintillator rods feeding into asingle photomultiplier tube, and provided a sufliciently effectivecross-section. One advantage of these small rod bundles is lowermanufacturing cost, because the rods could then be extruded.

However, there are additional advantages associated with the solid largecross-section logs. This type of log, as illustrated in FIGURE 6decreases the number of reflections which the light must encounter as ittravels between the point of origin and the photomultiplier tubecathode. Thus, there is light lost not only through transmission, butalso at the surface during each subsequent reflection. This is due tosurface imperfections and is a function of the number of reflectionsoccurring. Thus, the large cross-section causes the light to suffer lessattenuation, thereby reducing the differential in pulseheight. This isparticularly important, since the less attenuation of the light source,the better spectral resolution is obtainable.

FIGURE 9 shows the effect of the relative pulse-height of lightgenerated by the phosphor blocks compared to the distance from the endof the phosphor block.

The use of a photomultiplier tube at each end of the phosphor causes theoutputs of these tubes to be additive. Thus, as the pulse amplitude fromone tube decreases with increasing distance of photon origin from itscathode, the pulse-height is increasing at the other photomultipliertube. This decay or attenuation is exponential so that while the summedoutput is not flat, FIGURE 12, it still gives a greater degree offreedom from being effected by the position of photon origin.

The curve of the pulse-height of the light generated versus pulseorigin, FIGURE 12 is a rather fiat saddle, but has a marked upturn ateach end wiihin a few centimeters of each photomultiplier tube face.This is because light decay is due to a combination of exponents. Inaddition to the basic decay curve, there is also a rapid absorption ofcertain wave lengths in the first few centimeters from the point oflight generation in the phosphor log, which creates a wavelength shiftin the composition of light and gives rise to the sharp increase inpulse-height when the light originates next to a photomultiplier tubeface.

Elimination of this zone at both ends of log 60 is an important objectof this invention. In FIGURE 12 the eliminated zones A and B areillustrated graphically with respect to relative pulse-height anddistance from the respective log 60 ends. This is done by using a fourinch long truncated conical extension or light pipe 64 of the logs 60,mated at end 66 with the five inch circular photomultiplier tube faces.Extension or light pipe 64 is of the same plastic material as the mainphosphor, but contains no fluor. Thus, no gamma light conversion canoccur within four inches of the tube face. This eliminates any sharpincreases at the ends of the curve and keeps the differential betweenmaximum and minimum pulse height from the same gamma ray energy sourceto a minimum. This in turn increases the resolving power of the detectorlogs.

Because of the simplicity of shape of the detector logs utilized,mounting and placement of each of the detector units becomes relativelyeasy. This permits placement of the detector units in an optimumgeometric configuralion, and also provides adaptability of the entirecounter.

Each of the plastic phosphor logs is housed in a stainless steel channel63. The channel 63 forms a rigid lighttight case, and is longer inlength than the phosphor. It can thus be easily attached to a mountingring at the front and rear of the vault as illustrated in FIGUR-ES 1, 4and 5. The mounting ring produces the desired overall detectorconfiguration, and provides variability since increased detector areacan be had by inserting additional detector units. For carcass grading,a continuous flow detector tunnel can be formed of the rectangular logs.

In the past, careful washing and handling of each animal has beennecessary in order to prevent degrading the K determination by theinclusion of gamma count from Cs and other undesirable isotopes whichhave accumulated on the animals hair and hide. Such contaminantsmightoccur in nature or be caused by man made fall-out. This invention,however, increases the resolution of the phosphor detectors andelectronic equipment to the extent that such undesirable counts areexcluded and discriminated against electronically on the basis ofpulse-height (gamma ray energy level). This eliminates extra handling ofthe animal, but does not increase the time required for K countdetermination.

For example, FIGURE 7 illustrates the results obtained with a detectorwhich comprised a 6" X 6" X 60" log, with two photomultiplier tubes, oneat each end, but without light pipes. The effect of the undesired Cs atboth the center of the detection chamber as well as at end A (see FIGURE4), shows that the pulse-height of the Cs approaches the relatively highlevel of 85 at end A. This, of course, would cause an inaccuratedetermination of the lean-to-fat meat ratio, because much of themeasurement is due to the inclusion of gamma count from C FIGURE 8, onthe other hand, shows the increased resolution power from our improveddetector. This graph was prepared from measurements of a 6" X 6" x 60"log, of the type disclosed in FIGURE 6. The 05 pulseheights, at both thecenter and end of the log, are substantially lower, relative to the Kdistributed source count. This results in better resolution, allowingthe operator to scan a narrower range of the gamma ray spectrum, therebyincreasing the K noise ratio.

Our improved detector design also decreases the loss of K countscattered into the regions below the discrimination level used to rejectthe Cs FIGURE 8 shows that the discrimination level for Ca can besomewhere between 40 and 50. The K pulse height in this.

region is relatively low compared to the Cs pulse height within thisregion and hence the K count loss is minimized. However, above the 40-50pulse height discrimination level, the K distributed source accounts foralmost all of the gamma ray energy detected. However, in FIGURE 7, wherelight pipes were not used, Cs pulse-,

height at end A increased to about thereby precluding a low cesiumdiscrimination level. Thus, our detector geometry and shape results in amore accurate determination of the lean-to-fat ratio. It also increasesthe count efiiciency, which is defined as the percent of total K gamrnasemitted which are actually counted, because of the detector geometry andversatility.

What is claimed is: 1. A whole body scintillation detector and lightpipe especially adjustable for animal use which comprises:

(A) a plurality of highly polished plastic phosphor rectangular logdetectors arranged in a horseshoe configuration in a detection zone,with atleast one circular plastic phosphor detector mounted at one endof said zone; (B) a truncated conical section of plastic phosphorcontaining no fluor, mounted at each end of said logs as a light pipe;

(C) photomultiplier tubes mated to said truncated conical sections andto said circular phosphor detector,

said photomultiplier tubes being connected in electrical additiverelationship, whereby a source of radioactive energy striking saidplastic phosphor, produces a burst of light which travels along saidblock and is converted by said photomultiplier tubes to electricalenergy.

2. A scintillation detector as in claim 1, including a radioactiveshield positioned about said detector and said detection zone.

3. A scintillation detector as in claim 1, including means forimmobilizing and transporting an animal in and out of said detectionzone.

References Cited UNITED STATES PATENTS 2,711,482 6/1955 Goodman 250-71.5X 2,949,534 8/1960 Youmans 25071.5 3,035,172 5/1962 Cowan 250-7153,237,765 3/1966 Gaudin et al 25071.5 X 1 OTHER REFERENCES ARCHIE R.BORCHELT, Primary Examiner.

Gamma Counters and Their.

1. A WHOLE BODY SCINTILLATION DETECTOR AND LIGHT PIPE ESPECIALLYADJUSTABLE FOR ANIMAL USE WHICH COMPRISES: (A) A PLURALITY OF HIGHLYPOLISHED PLASTIC PHOSPHOR RECTANGULAR LOG DETECTORS ARRANGED IN AHORSESHOE CONFIGURATION IN A DETECTION ZONE, WITH AT LEAST ONE CIRCULARPLASTIC PHOSPHOR DETECTOR MOUNTED AT ONE END OF SAID ZONE; (B) ATRUNCATED CONICAL SECTION OF PLASTIC PHOSPHOR CONTAINING NO FLUOR,MOUNTED AT EACH END OF SAID LOGS AS A LIGHT PIPE; (C) PHOTOMULTIPLIERTUBES MATED TO SAID TRUNCATED CONICAL SECTIONS AND TO SAID CIRCULARPHOSPHOR DETECTOR, SAID PHOTOMULTIPLIER TUBES BEING CONNECTED INELECTRICAL ADDITIVE RELATIONSHIP, WHEREBY A SOURCE OF RADIOACTIVE ENERGYSTRIKING SAID PLASTIC PHOSPHOR, PRODUCES A BURST OF LIGHT WHICH TRAVELSALONG SAID BLOCK AND IS CONVERTED BY SAID PHOTOMULTIPLIER TUBES TOELECTRICAL ENERGY.